1. Industrial Field of the Invention
The present invention relates to apparatus for and method of correcting deformation of a gas turbine blade, capable of correcting or adjusting the deformation of a tip shroud of the gas turbine blade used for a generator by using a press.
2. Related Art
Gas turbine blades for generators are used under severe conditions, and for this reason, the material of the gas turbine blades deteriorates and deforms during a long time operation. Since the gas turbine blade is made of expensive heat resisting alloy, it is desirable in an economical viewpoint to repair and reuse deteriorated or deformed gas turbine blade as much as possible without discarding or newly manufacturing the blade. Regeneration by an HIP (Hot Isostatic Pressing) material reproduction treatment has been tried with respect to the material deterioration, and some extent of effect has been obtained.
On the other hand, without carrying out the correction to the deformation, the arrangement of circumferentially arranged gas turbine blades are changed so that adjustment is made to prevent the contact area of a tip shroud of adjacent gas turbine blades from becoming too small.
The deterioration of the material can be regenerated in some extent by employing the HIP material regeneration treatment. However, as the HIP material regeneration treatment utilizes an isotropic pressing technology by using gas, it is impossible to correct the deformation. Then, the arrangement of gas turbine blades is adjusted in consideration that the contact area of the tip shroud of the adjacent gas turbine blades does not become too small. Therefore, much time and cost are taken to adjust the arrangement, and even if the contact area is secured by the adjustment, it is difficult to entirely adjust the balance of gas turbine blades. In addition, there is the case where the contact area is not secured even if these gas turbine blades are suitably arranged as much as possible. In such a case, an expensive and new gas turbine blade must be applied to the portion difficult to adjust.
In the known art concerning such turbine blade deformation correction, at the time of manufacturing steam turbine blade or gas turbine blade through casting process, the correction of “twist distortion (strain)” or “bent distortion (strain)” caused particularly to an effective portion (i.e., portion at which steam or combustion gas as operation gas flows) of the blade has been performed by fixing the blade itself to a large-scale press and pressing thereby the blade (effective portion) from front and rear sides thereof. (For example, refer to Japanese Patent Laid-open No. HEI 6-262262 and No. HEI 8-276216).
However, in such prior art, the correction is mainly made to correct or adjust the distortion of the blade at newly manufacturing process or distortion only to the blade effective portion, and accordingly, it was difficult to apply such correction technology to the deformation of the blade tip shroud.